Most commercially-available electrical power can be characterized as either single-phase or three-phase. Both single-phase and three-phase power are generally available in industrial areas, but in rural areas and in many residential areas only single-phase power is generally available. Most industries which are connected to a three-phase source of power use three-phase motors. Therefore, as these industries upgrade or replace their equipment, used three-phase motors become available on the surplus market at a price substantially lower than that for a new three-phase motor or a new single-phase motor. However, these surplus three-phase motors are not useful to many potential users because of the cost of obtaining three-phase power and the cost of single-phase/three-phase converters.
Therefore, there is a need for a system which allows three-phase motors to be started and run from a single-phase power line.